The present invention relates generally to a method and apparatus for obtaining optimal performance in a receiver employing an automatic gain control system.
Cable television (CATV) receivers, such as set-top boxes, cable modems and cable telephony devices, employ automatic gain control (AGC) systems to provide constant power levels at the demodulator input. Within the AGC system, the power of the incoming signal within the desired channel is measured and used as a control parameter. Typically, incoming signals within channel assignments surrounding the desired channel may differ in amplitude, modulation type and presence. Since most existing AGC systems monitor only the amplitude of the incoming signal within the desired channel, non-optimal receiver performance is obtained given this limited view of the entire spectrum of incoming signals.
Thus, there exists a need to provide a method and apparatus that obtains optimal performance in a receiver employing an automatic gain control system.